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By Chris V. Sellathamby

Condition-based maintenance is replacing preventive maintenance in many industrial operations as a result of gains in productivity. Preventive maintenance is strictly time-based which means that as long as the prescribed time is sufficiently short, failures are prevented. The trade-offs between shorter cycles and increased downtime is a fine balancing act. Condition-based maintenance is gaining momentum as the more cost-effective and green solution to finding the optimal maintenance cycle and improving overall productivity. In the mining industry, various parameters of heavy equipment are monitored continuously to provide feedback for maintenance events. However, strain, shock, and vibration, key factors which lead to yielding and fatigue of metal parts, are not generally monitored by built-in systems, mainly due to the complexity of sensor installation and computational intensity of data processing. Scanimetrics has developed a stand-alone, add-on wireless system for measuring strain, shock, and vibration in heavy equipment and components, the data from which can be directly used to trigger maintenance events. The present system is being deployed in tar sands mining equipment. The system consists of a portable display and control unit, a software platform consisting of data management, sensor instrumentation and data analysis, and wireless strain sensor units, which can be easily installed on equipment. Data from the sensors can be gathered throughout the mine site, processed instantly, and used to generate condition-based maintenance events, improving overall uptime of the equipment and overall productivity of the mining operation.

Oct 1, 2010

By Kenneth E. Hay

Researchers from the U.S. Bureau of Mines conducted a field study to assess the safety of remotely controlled mobile roof supports (MRS) in a retreat pillar mining operation, Data were collected to provide the Mine Health and Safety Administration with criteria needed to develop guidelines for MRS use and to determine if precursors could be identified that would alert miners to imminent roof falls. Two test sites at which two different support methods-MRS's and posts were used and were monitored to obtain information on entry stability. Pressure transducers and string pots were installed on all four MRS's to obtain loading and displacement information. and roof bolt load cells. sonic probes, extensometers, and survey targets were installed in the surrounding entries to obtain information on ground behavior. Results showed a larger increase in roof bolt loading and roof movement when MRS's were used, especially in the intersection area. Roof bolt loads in the entries showed decreases in load when the MRS's were set and increases up to 11,1 kN (2,500 lbf) when the MRS's were unloaded. Unloading of one MRS in a pair did not significantly increase load on the other. MRS's I and 2 usually had the higher loads, with these loads increasing as the pillars on each side were being mined. MRS 3 normally had lower loads than I and 2: however, it also experienced some very high loads when in the last position near the pushout. MRS 4 usually had the lowest loads, primarily because it was located near the solid pillar that was not being mined.

Jan 1, 1995

By S. Devasahayam

Acid production or acid drainage is a major environmental issue that also has negative implications on the aquifer system surrounding the mine tailings area. The approach to controlling acid mine drainage involves physical and geochemical characterization that affect acid production. The material permeability determines the availability of oxygen, which is paramount in acid production in coal rejects, and varies with depth. In this paper the author presents the variation in oxidized pyrite/acid production with depth in black coal mine washery wastes. Chemical kinetic parameters and the diffusive parameters have been used to obtain the variation in oxygen content and the oxidized pyrite content with respect to the depth and time. Its dependence on porosity and moisture content is illustrated.

Jan 1, 2007

By Stephen L. Chryssoulis, Stamen Dimov

"Preg-robbing has been known for many years, where increased losses are suffered because dissolved gold is removed from solution by adsorption onto carbonaceous matter. In direct cyanidation circuits it is reasonable to conclude that the preg-robbed gold is either in a gold cyanide [Au(CN) - 2, AuCN] or metallic [Au°] form. However, in circuits with a pre-oxidation step possibilities increase and multiply even further because of water recycle streams containing apparent and not-so-apparent gold ligands. It is in these circuits where speciation of sorbed gold, i.e. the identification of the gold compound, is useful. The importance arises from the fact that proper identification of the sorbed gold species can be used to determine how, when, where and why gold was removed from solution, thereby identifying the exact cause of the problem and providing clues as to how it may be rectified.INTRODUCTIONTo the best of our knowledge, this is the first attempt ever to speciate gold preg-robbed by carbonaceous matter using a surface sensitive microbeam technique. This approach enables the direct determination of gold species sorbed on carbonaceous particulates, opening an entirely new field in the understanding of the chemistry of gold sorption on carbon. The reasoning behind this effort was to add to the current knowledge of the detrimental effect chloride ions have on gold recovery by the pressure oxidation and in particular why in the ensuing CIL step, gold is not being desorbed from the surface of the carbonaceous particles (Table 1)."

Jan 1, 2004

By V. C. Perini

The North Central Texas district as herein defined includes the counties of Brown, Callahan, Coleman, Comanche, Coryell, Eastland, Erath, Fisher, Hamilton, Haskell, Hood, Jones, Lampasas, Mills, Nolan, Palo Pinto, Parker, San Saba, Shackelford, Stephens, Stonewall, Summer-ville, Taylor, Throckmorton and Wise. These counties as listed are the counties of District 7B, State Railroad Commission. In the new designation of districts for the Transactions, the North Central Texas district includes most, but not all, of the counties of the previously classified West Central Texas district. This district covers the south central crest and the west flank of the Bend flexure north of the Llano uplift. The west flank of the Bend flexure is on the east boundary of the Permian Basin of West Texas. The greater part of the oil and gas produced in this district has been from Pennsylvanian strata. Some oil and gas has been produced from the lower Permian (by the latest, selection of the Pennsyl-vanian-Permian boundary) and minor amounts from the Mississippian and Ordovician sediments. Increasingly important quantities of oil and gas are to be expected from the older sediments by deeper development in proven fields and by new discoveries. Most of the oil and gas in the district has accumulated in localized, well-defined structural traps in limestone and sandstone reservoirs and in traps due to stratigraphic changes in sedimentation, mainly porosity traps in limestone and sandstone lenses, both usually associated with some structural feature. These features are found by surface and subsurface geological structural mapping, by core drilling and by geophysical surveying. Geochemical methods are also the basis for some wildcatting. The demand for sweet crude oil from this district is firm for local and national consumption, but the market price for the oil remains practically the same as in 1941. The price is not adequate to meet the requirements of the average independent operator with the continued advance in production, tievelopment and wildcatting costs. Stripper wells are being plugged daily and should be jealously saved for the future local and national reserves, especially in view of the fact that new discoveries of commercially important oil and gas reserves are not keeping pace with consumption. An expected economic disruption attendant upon the national war effort has arisen and continues in the future outlook for this district. The lack and delay of securing replacement parts for almost all oil-field equipment has handicapped and delayed operations and has decreased efficiency in wildcatting, development and production. Sufficient experienced drilling, scientific and office personnel is lacking because of inductions in the armed forces and migration to war industries during the period before manpower conservation became effective. The office personnel of the average oil and gas producer continues to be swamped by the increasing demands for reports by state and federal bureaus. An average of IQ days

Jan 1, 1944

By V. C. Perini

The North Central Texas district as herein defined includes the counties of Brown, Callahan, Coleman, Comanche, Coryell, Eastland, Erath, Fisher, Hamilton, Haskell, Hood, Jones, Lampasas, Mills, Nolan, Palo Pinto, Parker, San Saba, Shackelford, Stephens, Stonewall, Summer-ville, Taylor, Throckmorton and Wise. These counties as listed are the counties of District 7B, State Railroad Commission. In the new designation of districts for the Transactions, the North Central Texas district includes most, but not all, of the counties of the previously classified West Central Texas district. This district covers the south central crest and the west flank of the Bend flexure north of the Llano uplift. The west flank of the Bend flexure is on the east boundary of the Permian Basin of West Texas. The greater part of the oil and gas produced in this district has been from Pennsylvanian strata. Some oil and gas has been produced from the lower Permian (by the latest, selection of the Pennsyl-vanian-Permian boundary) and minor amounts from the Mississippian and Ordovician sediments. Increasingly important quantities of oil and gas are to be expected from the older sediments by deeper development in proven fields and by new discoveries. Most of the oil and gas in the district has accumulated in localized, well-defined structural traps in limestone and sandstone reservoirs and in traps due to stratigraphic changes in sedimentation, mainly porosity traps in limestone and sandstone lenses, both usually associated with some structural feature. These features are found by surface and subsurface geological structural mapping, by core drilling and by geophysical surveying. Geochemical methods are also the basis for some wildcatting. The demand for sweet crude oil from this district is firm for local and national consumption, but the market price for the oil remains practically the same as in 1941. The price is not adequate to meet the requirements of the average independent operator with the continued advance in production, tievelopment and wildcatting costs. Stripper wells are being plugged daily and should be jealously saved for the future local and national reserves, especially in view of the fact that new discoveries of commercially important oil and gas reserves are not keeping pace with consumption. An expected economic disruption attendant upon the national war effort has arisen and continues in the future outlook for this district. The lack and delay of securing replacement parts for almost all oil-field equipment has handicapped and delayed operations and has decreased efficiency in wildcatting, development and production. Sufficient experienced drilling, scientific and office personnel is lacking because of inductions in the armed forces and migration to war industries during the period before manpower conservation became effective. The office personnel of the average oil and gas producer continues to be swamped by the increasing demands for reports by state and federal bureaus. An average of IQ days

Jan 1, 1944

By L. G. Marshall

This report describes dredging and processing of sand and gravel from a glacial-fluvial deposit in the Raccoon River valley near West Des Moines, Iowa. Preliminary cleaning and separation of the sand and gravel at the dredge site with subsequent transportation to separate plants and the production and disposal of the various grades of aggregate material are also described. The geology of the deposit is summarized. A tabulated summary of costs in units of labor, power, and supplies is included.

Jan 1, 1963

By Gary Buchan

"Mine-wide ground control stability is essential to any mining operation to prevent catastrophic failure of underground structures. The ability to recognize or indicate the potential for ground control hazards in underground mine operations is highly desirable to reduce or eliminate ground-control-related injuries and fatalities. The acoustic emissions (AE) form of non-destructive testing has been used for decades to determine material or machine deterioration or potential failure. This paper presents the findings of research in AE with the results of laboratory bolt pull tests and comparisons to field experimentation, including AE sensors and bolt load data in an underground stone mine. The goal of the project is to compare laboratory results of AE sensors on roof bolt pull tests with field experimentation to determine the capability of predicting bolt failure or roof deterioration.INTRODUCTIONMine-wide ground control stability is essential to any mining operation to prevent catastrophic failure of underground structures. The ability to recognize or indicate the potential for ground control hazards in underground mining operations is highly desirable to reduce or eliminate ground-control-related injuries and fatalities. Typical ground control monitoring devices involve drilling into roof or rib, grouting or gluing of sensors, and dedicated cabling for data collection. One of the original goals of this research was to develop a methodology for a simple wireless device that could provide an indication or warning of potential roof bolt or roof failure. Various types of nondestructive testing (NDT) have been used for decades to determine material or machine deterioration or the potential failure of either. One type of NDT is acoustic emission (AE) monitoring, which has been studied for use in mining to predict rock bursts and mine failures since the 1940s (Obert, 1941; Obert and Duvall, 1942). The primary goal of the work was to compare laboratory results of AE sensors on roof bolt pull tests with field experimentation to determine the capability of evaluating bolt loading or roof deterioration in an underground stone mine. Bolt pull tests were conducted in the laboratory to establish a repeatable trend of AE activity versus bolt load. The second part of the project was to then install bolt load cells in an underground stone mine and monitor AE activity in the vicinity of mining."

Jan 1, 2018

By Jun-Yan Chen, Stefan H. Boshkov

Metal mining in the People's Republic of China has shown great growth during the last three decades. Over 150 new iron ore mines and nonferrous base metal mines have been opened since 1949, althouc.11 most of them of medium and small size. Concurrently, many old mines were enlarged and reconstructed. The production of iron ore has grown from less than 1.5 million tons per year in 1949 to almost 76 million tons in 1978. A corresponding increase in the total annual output in the nonferrous metal mineral industry has also been noted. It is well known that the PRC is very rich in metal mineral resources. The reserves of tungsten, tin, antimony, molybdenum and iron ore are ranked in the top three in the world. Recently, some copper porphyry ore deposits were discovered in Jianxi and Anhui provinces. Some large nickel-copper sulfide deposits were discovered and have been developed in North- West China. Huge iron ore deposits have been found in Liaoning, Hebei and Szechwan provinces. However, the bulk of the iron ores are low grade. The growing metal mineral production has met basic domestic needs since 1949; it has also proven China's big resource potential. Mining methods have also undergone development in the past 30 years. About 80% of the annual output of iron ore comes from open pits, whereas about 58% of nonferrous metal ores come from underground mines. Blasthole open stoping, sublevel caving and induced block caving are widely used in Chinese underground metal mines (table 1). This paper summarizes in detail the planning for and application of these three bulk mining methods in the nonferrous and iron ore mines in China. CLASSIFICATION OF UNDERGROUND MINING METHODS The main principle of the classification of underground mining methods in PRC is ground support in the stoping cycles of the mining blocks or stopes. Table 2 lists this classification. It is essentially the same as that given in the SME Mining Engineering Handbook. Be- cause pillar removal is a secondary mining operation, using a variety of methods, they are not included in this classification. As is the case with most classifications in science and technology, there is no precise division between the classes of mining methods. Because of the rapid development of consolidated filling techniques in the past twenty years, some types of open stoping methods use fill in order to improve the ground conditions for the secondary recovery stage. Thus, these mining methods have features of both methods using no artificial support and those using artificial support. In this classification, this type of mining method is placed in the latter category. The shrinkage stoping method has been employed extensively to mine steeply dipping narrow veins of tungsten and tin in the Jiangxi, Hunan, Guangdong and Guangxi provinces. Shrink- age stoping is placed under the class of mining methods without artificial support be- cause this reflects the nature of the Chinese experience. The function of the broken ore serving to support the footwall and/or hanging wall is limited, because the expectation is for the host rocks to remain unsupported until the stope is drawn empty. APPLICATION OF BULK MINING METHODS Bulk mining methods consist of blasthole open stoping, sublevel caving and block caving. These stoping methods have much in common, such as: bulk ore materials blasted by long holes; higher production rates of stopes or blocks and higher production efficiencies of the whole mining systems.

Jan 1, 1981

By Bernard Hertlein

¦ Drilled shafts resist scour seismic loads better than groups of driven piles ¦ Drilled shaft construction creates less noise and vibration than driving piles ¦ Drilled shafts permit direct observation of bearing stratum, and confirmation of location ¦ Drilled shafts are cost effective

Jan 1, 2001

By David S. Graham, Joseph D. Bailey, Paul J. Axtell, Michael K. Muchard

"Two instrumented test piles were simultaneously subjected to a static lateral load test by jacking the piles apart. One of the piles was loaded in axial compression via kentledge during the lateral load test. Both piles were constructed in an identical manner. These piles were constructed and tested as part of a construction-phase load test program for a floodwall improvement project along the Missouri River in Kansas City, Kansas. Details of the subsurface conditions, drilled pile construction, instrumentation, and load testing procedures are described. Data collected during testing of the piles are presented and compared. Potential effects of the axial compressive load related to observed differences in pile lateral response are discussed.INTRODUCTIONTwo instrumented test piles were simultaneously subjected to a static lateral load with one of the piles also subject to a combined axial load during testing. The load test program was part of a floodwall improvement project in Kansas City, Kansas. Known as the BPU floodwall, the floodwall runs along the south bank of the Missouri River at a Kansas City Board of Public Utilities power generation and water treatment facility. The project location is shown in Fig. 1.Drilled, 2-ft (610-mm) diameter piles were designated by the designer, the U.S. Army Corps of Engineers (COE), as the foundation type for supporting extended floodwall footings. The drilled piles are fully cased, cast-in-place concrete, reinforced with a steel 12x74 (310x110) H-pile. In order to test soil lateral response and pile structural response under combined loading, the COE required that both a lateral test and combined lateral and axial test pile be constructed and tested. In order to most efficiently test both piles and to allow for simpler comparison, the two piles were simultaneously laterally loaded by jacking the piles apart, applying a maximum lateral load of 195 kips (867 kN). A constant axial load was applied to the combined test pile by kentledge prior to lateral loading and was maintained for the duration of the lateral load test. The total weight of the kentledge was 61.5 kips (274 kN). Fig. 2 shows the test setup."

Jan 1, 2017

By John Relser

The production processes that are developed in the mining and minerals industry are manufactured to be exposed to very aggressive environments. Chemical, abrasion, and impact expose structures and equipment, steel or concrete, to a significant deterioration. This causes damage and adds high costs to operations that can be reflected in the destruction of equipment and structures in the arrest of the production process, which becomes very costly. Also, there is the potential for personnel accidents, which would require large sums of compensation for an employee, thus directly harming the image of the mining operation and company. Manufacturers of paints and coatings that have major centers for research and development (R&D Labs) distributed globally have developed high-tech products for durable protection from the elements for structures and equipment used in the mining industry. The difference between these paintings and coatings and what is normally known as conventional paints (e.g., those called domestic or decorative), is its chemical composition, structured around polymeric components that have highly resistant, chemical and physical properties to cope with extreme conditions to which they are exposed. With this, and only this, longer life of components can be achieved for equipment and structures used in the production processes of the mining industry. Today, in addition to the important features mentioned, some manufacturers of the paints and coatings dedicated to this highly modernized process have invested large sums of money in developing new products that add operational elements to the painting process. These coatings provide added value and significant performance to companies mining operations and that we can describe in three fundamental concepts:

Feb 1, 2014

By G. B. Harris

A new process for the recovery of copper and associated base metals from a polymetallic massive sulphide ore is described. The massive sulphide contains copper and especially nickel sulphide in a mineralogical form which negates both good recovery and high grades in concentrates using conventional flotation methods. Flotation concentrate processing and smelting from this ore is therefore probably not an economically viable option. Utilising the properties of high concentration chloride brines, a flow sheet has been developed and tested whereby the recovery of all of the metals and some of the power requirements for the plant itself can be derived from the ore. The new process overcomes the less-amenable-to-flotation ore characteristics, and provides the opportunity of economic processing in remote locations where the dependency on fossil fuels is both a logistical and an economic concern. The Ferguson Lake deposit of Starfield Resources in Nunavut, Canada, is the subject of this paper, which focuses on the leaching and copper recovery unit operations of the proposed flow sheet.

Jan 1, 2007

By B. P. Faulkner, M. Weinecke

Svedala started a development program in 1997 to develop a process to convert waste tires into valuable commodities. A review of numerous approaches revealed short-comings in the various approaches either process, mechanical, combination of factors, or trying to emphasis the production of low value products. A market study revealed that a process that could produce a good grade of carbon black would be economically feasible. This paper discusses the laboratory and pilot plant development and commercial plant design.

Jan 1, 2001

By R. N. O'Brien, E. Peters

"It has been discovered that copper concentrates can be leached in strong (40-60%) sulfuric acid with nitric acid, or with oxygen if nitric acid is present as a catalyst. Chalcopyrite is rapidly decomposed at temperatures well below the boiling temperature of the lixiviant (-150 C.) and the resulting copper and ferric salts are precipitated as CuS04.H20 and FeH(S04)z.4H20. Other metal sulfides such as zinc, lead, nickel, etc. are also converted to sulfates that are nearly insoluble. Sulfur is partially converted to elemental and partially to sulfuric acid. Reduction products of nitric acid can be recovered from the distillate with good recovery. Conversion of as-received copper concentrates is largely complete in about 1 hour. Introduction9 molar sulfuric acid is an unusual hydrometallurgical lixiviant: it has a boiling point of about 150 C. and a low solubility for base metal sulfates. Below about 6 molar acid, the boiling point falls below 120 C. and yields much higher sulfate salt solubility, while above 12 or 13 molar acid and at higher temperature sulfuric acid becomes an oxidizing agent, yielding gaseous S02' Thus, sulfuric acid within this range of concentration is capable of acting well above the temperature of boiling water without requiring autoclave conditions, and if typical oxidative leaching conditions are applied to suspended mineral sulfide concentrates, it is possible to obtain a conversion of these sulfides into 'crystalline sulfates. Thereafter, the sulfates can be separated by filtration or by solid - bowl centrifuge and the solution can be recirculated to the reactor vessel. Meanwhile, the solid sulfates can be treated in a typical hydrometallurgical circuit, i.e., dissolved in a return stream that is essentially water, separated from each other by, for example, solvent extraction, and recovered as metals by electrowinning."

Jan 1, 1997

By Worthen Bradley, R. G. Hall

THIS paper will attempt to show how a metallurgical problem at one California quicksilver mine was solved, and how the solution was applied successfully at another mine. The pronouns "we" and "our," as used below, refer to the Bradley Mining Co. of San Francisco. The term "concurrent firing" for the purpose of this paper can be defined as feeding and firing a rotary kiln at the same end-that is, of course, the upper end. This is as opposed to "counter-current firing," the orthodox method, in which a kiln is fed at the upper and fired at the lower end. The terms "quicksilver" and "mercury" are used interchangeably. EARLY REFERENCES The earliest work on nonferrous metallurgy, we believe, was The Pirotechnia of Vannocio Biringuccio,1 its first edition having been printed in Italy in 1540. Quoting from its chapter entitled "Concerning Quicksilver and Its Ore": Quicksilver . . . is one of the gods and has divine strength in itself, and also, to the annoyance of the alchemists, it is winged. Hence, when it sees that it is in gravest danger, it loosens itself from . . . every bond . . . and flies away into the heavens, escaping from the hands of those who crucify it. Almost laughing, it leaves all its adversaries mocked and scorned, with their phials and filters empty . . . How thorough a job, under certain conditions, it can do of mocking its adversaries and leaving their phials and filters empty, was found out four centuries later at the Sulphur Bank mine, on the east shore of Clear Lake, in Lake County, California. The other mine mentioned in the title is the Reed, in Yolo County, California, 35 miles by road southeast of Sulphur Bank. Reed and Sulphur Bank ranked respectively fifth and seventh in U. S. production in 1943. The earliest direct reference we can find to furnacing troubles at these mines was by Thomas Egleston in 1890.2 Speaking of Sulphur Bank, Egleston says: Sometimes there is more sulphur than cinnabar in the ore, which is a detriment to both . . . making the sulphur impure, and rendering the cinnabar difficult to work on account of the soot. In some of the early . . . furnaces the accumulation of soot from the excess of sulphur has been known to penetrate as far as the fan blower at the end of the . . . condensers, and completely prevent its revolution. In order to get rid of the inconvenience of this accumulation . . . , as well as to get a commercial value from the sulphur, it (the sulphur) is now separated by steam and sold. It is claimed that the sulphur alone pays all the expenses of . . . the mine. The mine was first worked for sulphur, and the cinnabar it contained was considered to be an inconvenience, and was carefully picked out and thrown away. as its richness and value were not

Jan 1, 1945

The Effect of Using Different Comminution Procedures on the Flotation of Platinum Group Minerals The use of High Pressure Grinding Rollers (HPGR) has been widely reported to have major benefits in the treatment of minerals such as iron ore and diamonds. To date there have been few investigations into its use in the treatment of ores containing Platinum Group Minerals (PGMs). HPGRs are known to reduce energy consumption and wear costs and improve the throughput in the circuit. In the present investigation the effect of the comparative use of HPGR and conventional crushing in combination with either dry or wet rod milling on the flotation of PGMs was studied using batch flotation. Previous studies of a base metal sulfide ores had shown that either HPGR or conventional crushing followed by dry milling produced the highest grades and recoveries. However in the present study it was observed that a similar treatment produced the worst results and the highest grades and recoveries were obtained for the case of conventional crushing in combination with wet milling. The HPGR showed no advantages in terms of flotation performance and dry milling produced particularly poor flotation results. The results were investigated further using various surface characterisation techniques in order to determine the reason for the decrease in grades and recoveries of platinum when using dry milling and HPGR as opposed to the case for base metal sulfides. The feed and product samples were analysed using ToF-SIMS, XPS and MLA. The paper will propose reasons to explain the different flotation behaviour of the two ore types following the various comminution processes focusing on the surface characteristics of the ores, the particle size distribution and the pulp chemistry.

Sep 13, 2010

By Sergio Godoy P.

The Los Bronces porphyry copper deposit is located in the high Andes of Central Chile. Ore is mined from several tourmaline breccias and from an earlier porphyry. After years of experience in the geostatistical estimation of reserves in different zones of the ore body, we believe that success lies in considering the evaluation as an integrated process beginning with the analyses of the drilling density and sampling methodology, ending with the critically important reconciliation between the estimated and the actually extracted ore, in general, when errors or differences occur, focus is centered in the calculation stages of geostatistics. However, this paper demonstrates that all the evaluation stages are equally important and require the direct and continuous geologic input to ensure the best possible estimate within the frame of the geologic constraints.

Jan 1, 1992

By J. D. Miller, R. J. Smith

The hot water process for Utah tar sands differs significantly from that used for Canadian tar sands due to inherent differences in respective bitumen viscosities and the nature of bitumen-sand association. These differences have led to the identification of certain design criteria necessary to achieve satisfactory phase disengagement during digestion (Sepulveda and Miller, 1978; Misra and Miller, 1980). Subsequent flotation of digested tar sand is a subject of current attention and is considered in this publication for the Asphalt Ridge deposit. Although contact angle measurements of solvent extracted Asphalt Ridge bitumen indicated moderate hydrophobicity, air bubble attachment to the bitumen concentrate is not possible. This surprising result suggests that flotation separation is dependent on air bubble entrapment rather than on air bubble attachment due to surface hydrophobicity. The entrapment of air bubbles in the bitumen was apparent from examination of the bitumen concentrate, especially at lower flotation temperatures. A factorial design of the major operating variables in flotation separation indicated that the quality of separation was significantly dependent on the flotation temperature and to a lesser extent on the degree of agitation. For a flotation temperature of 77°C a recovery of 96.7% was realized at a grade of 61.0% bitumen. The improved separation at higher flotation temperatures was found to be due to the decrease in bitumen viscosity resulting in more effective rejection of coarse sand from the concentrate. This research effort, which has been sustained for the past six years at the University of Utah, is being continued to provide necessary design data for the construction of a pilot plant to treat Utah tar sands.

Jan 1, 1982

By G. M. Swinkels, A. Vizsolyi, E. Peters

A process is described utilizing ferric chloride leaching followed by reduction of the cupric content to cuprous by cement copper, with CuCl obtained thereafter by crystallization. The residual liquor is cemented with sponge iron to produce cement copper and a copper free ferrous chloride solution. The latter is oxidized in an autoclave with oxygen to regenerate ferric chloride and to precipitate excess iron as a granular, filterable hematite. Cuprous chloride crystals are reduced to high purity metal with hydrogen, while sulphur reports almost quantitatively in residues in the elemental form. Pyrite and molybdenite are not leached. This paper describes the important variables in the process, as well as the deportment of minor elements as silver, gold, selenium, tellurium, bismuth, nickel, lead, zinc, magnesium, etc. An elegant method of isolating silver from CuCl crystals is described, as well as recovery of gold from residues by a chloride reagent The process is described as non-polluting and capable of producing refined copper, ore grade iron oxide, elemental sulphur, and yields of minor metals as good or better than obtainable by conventional smelting, without the use of solvent extraction or electrochemistry.

Jan 1, 1981